JPH078136Y2 - Diamond tools - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to improvement of a diamond tool.

[Conventional technology and its technical problems]

When forming a finishing hole in a part or member, it is common to drill a pre-drilled hole in the work in advance and finish it in the next process, and with the refinement of the product, a small diameter with good surface roughness and dimensional accuracy. A hole is required. There is a reamer as this kind of processing tool, but as is well known, it is a tool steel shaft-shaped main body with blades that are parallel to the axis or twisted, so it is difficult to maintain surface roughness and accuracy. There is a problem that the life is short and honing finish is required separately to improve the surface roughness.

As a countermeasure against this, a tool in which fine diamond abrasive grains are electrodeposited and fixed on the surface of the tool body is known. However, since the conventional diamond tool has a structure in which diamond abrasive grains are simply electrodeposited and fixed to the main body, the dimensions such as the hole diameter to be processed become unstable, and the surface roughness is determined by the grain size of the abrasive grains. However, there is a disadvantage that it is necessary to prepare a tool in which various kinds of abrasive grains are electrodeposited in the order of finishing process. Further, since it is necessary to use fine abrasive grains for top finishing, clogging is likely to occur during machining, and this clogging causes the machined surface to be rough and deteriorates accuracy. So diamond tools can only be used for rough finishing,
After all, it was necessary to finish by honing.

As a countermeasure against this, the present inventor proposed in Japanese Patent Application No. 62-154054 a tool in which each abrasive grain protruding portion of the straight portion of the tool body was cut concentrically to form a flat ridge line. It has become possible to eliminate the drawbacks considerably. However, this tool has a strong degree of change in the cutting edge, that is, rough cutting by the uncut tapered abrasive grains of the cutting edge causes "leveling" by the straight straight abrasive grains of the cutting edge, so it is inevitable There is a problem that a local portion having a rough surface is likely to remain on the surface, and the abrasive grains in the straight portion are likely to be dropped or crushed due to the cutting load.

The present invention was devised to solve the above problems, and the purpose thereof is to use one kind of coarse abrasive grains as the abrasive grains and to finish with high precision and extremely in one step. It is possible to process surface roughness in good condition,
At the same time, it is to provide an inexpensive diamond tool capable of increasing the cutting amount, improving the surface roughness, and achieving high accuracy.

[Means for Solving the Problems]

In order to achieve the above object, the present invention provides a tool having abrasive grains adhered to the outer periphery thereof, wherein a straight portion is provided on the rear end side of the tool and a second taper portion having a small tip is provided on the tip end side of the tool, A first taper portion having a smaller inclination angle than the second taper portion is provided between the straight portion and the second taper portion, and the straight portion, the first taper portion and the second taper portion each have a granularity. While fixing one kind of relatively coarse abrasive grain, the abrasive grain group of the second taper portion has a sharp cutting edge without being cut, and the abrasive grain group of the straight portion and the first taper portion The abrasive grain group has a cutting edge provided with a ridge and a cylindrical surface having the tool axis as the central axis by cutting the projecting portion with the cylindrical surface having the tool axis as the central axis that matches the finishing hole diameter, And the cutting edge of the first taper part is close to the straight part. Large cut margin, is obtained by a configuration in which cutting margin is smaller closer to the second tapered portion.

The cutting degree of the abrasive grains in the first taper portion is appropriately set to, for example, about 1/8 to 1/4 of the abrasive grain height.

[Action]

When the tool body is rotated and the work or the tool is fed, the work is first cut by the second group of sharp abrasive grains having a taper. This cutting surface is rough, and there are many streaky cuts. Then, when the first taper portion advances, the tip of the abrasive grain group in this portion is shallowly cut on the cylindrical surface with the tool axis as the central axis, and therefore the uncut portion in the preceding stage is left uncut by the ridge line at the edge of the cylindrical surface. Since the abrasive grains in this portion are cut and are closer to the tool diameter toward the rear in the axial direction, the cutting amount is gradually reduced, and adjustment is made so as to leave some uncut residue.

Then, the straight portion advances next, and the abrasive grain group in this portion is cut with a cylindrical surface centered on the tool axis with a diameter that matches the tool diameter, so some cutting residue left on the cutting surface is negative It is cut, resulting in a very smooth finished surface.

〔Example〕

 An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an embodiment in which the present invention is applied to a reaming hole drilling tool. In FIGS. 1 and 2, 1 is a tool body (base metal) made of tool steel or the like, It is attached to the spindle 6 by a shank 10 which is integrally formed so that a required rotation and thrust force can be given. Reference numeral 2 is a work, in which a prepared hole 20 to be finished is formed.

As shown in FIG. 2, the tool main body 1 has a straight portion 1a at the rear end and parallel to the axis, and a first portion at the front end side following the straight portion 1a.
The tapered portion (intermediate taper part) 1b and comprises a second tapered portion or (main tapered portion) 1c, a gradient alpha ₁ of the first taper portion 1b, the gradient alpha ₂ of the second tapered portion 1c The relationship is α ₁ > α ₂ .

On the surfaces of the straight portion 1a and the first and second tapered portions 1b and 1c, a large number of diamond abrasive grains 3 having a relatively coarse grain size are held and fixed by bonds 4 such as nickel plating. Also, from the straight portion 1a to the second taper portion 1c
A plurality of spiral grooves 11 having large leads are formed.

As shown in FIG. 2 and FIG. 3 (a), the diamond abrasive grain group 3a of the straight portion 1a conforms to the tool outer diameter (that is, the finish machining hole diameter) D on the basis of the one having the lower protruding height. Each projecting part 30,3 on the cylindrical surface 5 with the tool axis as the central axis
0 is cut (polished) into a plane. Note that FIG. 2 shows the taper in an emphasized manner.

On the other hand, the abrasive grain group 3b of the first taper portion 1b has a cylindrical surface 5'having the same tool axis as the tool outer diameter D as the central axis, as shown in FIGS. 2 and 3 (b). The protruding portions 30, 30 are shallowly cut (polished) in a planar shape. The degree of this cut is determined by the gradient of the first taper portion 1b, but it is generally preferable that it is, for example, about 1/8 to 1/4 of the dimension d of the abrasive grain working direction.

In any case, due to the gradient α ₁ , FIG. 5 (a) (b)
As described above, the cutting margin is larger as it is closer to the straight portion 1a, and the cutting margin is smaller as it is closer to the second taper portion 1c.

Therefore, each of the straight portion abrasive grain group 3a and the first taper portion abrasive grain group 3b has a cylindrical surface 31 (which is flat as shown in FIG. 4) having the tool axis as the central axis. The ridgeline 32 at the outer edge of the flat surface 31 constitutes a large number of linear cutting edges in the axial direction and the circumferential direction, and the abrasive grains 30a and 30b individually serve as negative cutters.

[Operation of Example]

 Next, the operation of this embodiment will be described.

In FIG. 1, the tool is mounted on the spindle 6,
Rotation and axial feed are provided. The hole diameter of the prepared hole 20 is enlarged by cutting with the abrasive grain group 3c of the second tapered portion 1c. At this stage, the abrasive grain group 3c has a sharply edged cutting edge, so the ground surface is a rough surface with many protrusion marks.

The first tapered portion 1b subsequently advances to the cut portion by the second tapered portion 1c. The diameter of the first tapered portion 1b is continuously increased from the second tapered portion 1c and the gradient is gentle, and the abrasive grains 3b on the surface have protruding portions on a cylindrical surface whose center axis is the tool axis. By cutting only about 1/8 to 1/4 of the abrasive grain size, a flat cylindrical surface 31 and a ridge line 32 forming a straight blade
have. Therefore, in this first tapered portion 1b, the protruding portion in the hole left uncut in the previous stage is cut by the ridge line 32 until it contacts the cylindrical surface 31, and the protruding height to the cylindrical surface 31 becomes the second tapered portion 1c. The closer it is, the larger it is, so the protruding part in the hole is gradually scraped away as the tool advances. That is, the first tapered portion 1b exerts an intermediate leveling action on the machined surface.

Then, following the first tapered portion 1b, the straight portion 1a
When entering the prepared hole, the abrasive grain group 3a in this straight portion 1a has a larger outer diameter than that of the first tapered portion 1b, and the outer periphery forms a cylindrical surface 31, and its ridge line 32 causes a negative linear blade. Since a large number of abrasive grains 3a are formed and are randomly arranged, the abrasive grain group 3b of the first taper portion 1b is formed.
The roots of the protrusions left uncut in step 1 are ground uniformly in a plane. Since the cylindrical surface 31 of the abrasive grain group 3a matches the tool outer diameter D, it functions to cut only the protruding portion of the inner diameter surface,
No further grinding is done.

That is, cutting ends when the cylindrical surface 31 of each abrasive grain hits the hole wall uniformly, the outer diameter of the tool and the inner diameter of the workpiece become the same, and an extremely flat finished surface is formed on the workpiece side. The straightening by the straight portion 1a is performed by cutting the root of the portion in which most of the protruding portion was previously cut off by the first taper portion 1b in the previous stage. Therefore, the load is small, and the abrasive grains are unlikely to crack or crush.

Due to these characteristics, high-precision holes with excellent surface roughness and stable dimensions are formed in one stroke.Because of the above cutting edge characteristics, it is possible to perform fine surface roughness processing with coarse abrasive grains, which results in clogging. No worries and good grindability can be obtained. The generated chips are discharged to the outside through the spiral groove 11.

[Effect of device]

According to the present invention described above, the straight portion 1a is provided on the rear end side of the tool, and the second taper portion 1c having a small tip is provided on the front end side of the tool.
The first taper portion 1b having a smaller inclination angle than the second taper portion 1c is provided between the second taper portion 1c and the second taper portion 1c, and the straight portion 1a, the first taper portion 1b and the second taper portion 1c are provided. The relatively coarse abrasive grains 3 each having a single grain size are fixed to each other, and the abrasive grain group 3c of the second taper portion 1c has a sharp cutting edge without being cut, and the abrasive grains of the straight portion 1a are The group 3a and the group 3b of abrasive grains of the first taper portion 1b have the tool axis as the center line by cutting the projecting portion 30 with a cylindrical surface having the tool axis as the center axis that matches the finishing hole diameter D. It has a cutting edge having a cylindrical surface and a ridge line 32, and the cutting edge of the first taper portion 1c has a larger cutting allowance as it is closer to the straight portion 1a.
Since the cutting margin becomes smaller as it gets closer to the taper portion, the following excellent effects can be obtained.

Despite the use of one type of coarse-grained abrasive grains, it is possible to continuously perform rough surface finishing to fine surface finishing in one step to obtain a good surface roughness.

Since it is possible to finish with fine surface roughness only by using one type of coarse abrasive grain, it is possible to reduce the manufacturing cost and the finishing process cost.

Since one kind of coarse abrasive grain is used, the pockets of rough finish, middle finish and fine finish are large, and a large amount of cutting waste can be endured, eliminating the risk of clogging. Therefore, it is possible to increase the speed by increasing the cutting amount, improve the surface roughness, and achieve high accuracy.

[Brief description of drawings]

FIG. 1 is a side view showing an example of a diamond tool according to the present invention, FIG. 2 is an enlarged sectional view of the same, and FIG. 3 (a).
(B) and (c) are cross-sectional views of each part in FIG. 1, FIG. 4 is a cross-sectional view showing abrasive grains of the straight part in FIG. 3, and FIG. 5 (a) (b)
FIG. 4 is a cross-sectional view showing the abrasive grains of the first tapered portion of FIG. 1 ... Tool body, 1a ... Straight part, 1b ... First taper part, 1c ... Second taper part, 3a ... Abrasive grain group of straight part, 3b ... Grinding of first taper part Grain group, 3c ... Abrasive grain group of second taper part, 31 ... Cylindrical surface, 32 ... Ridge line

Claims (1)

[Scope of utility model registration request] 1. A tool having abrasive grains adhered to the outer periphery thereof, wherein a straight portion 1a is provided on the rear end side of the tool, and a second taper portion 1c having a small tip is provided on the tip end side of the tool. The first taper portion 1b having a smaller inclination angle than the second taper portion 1c is provided between the second taper portion 1c and the second taper portion 1c, and the straight portion 1a, the first taper portion 1b and the second taper portion 1c are provided. The relatively coarse abrasive grains 3 each having a single grain size are fixed to each other, and the abrasive grain group 3c of the second taper portion 1c has a sharp cutting edge without being cut, and the abrasive grains of the straight portion 1a are The group 3a and the group of abrasive grains 3b of the first taper portion 1b have the tool axis as the central axis by cutting the projecting portion 30 with a cylindrical surface having the tool axis as the central axis that matches the finishing hole diameter D. It has a cutting edge having a cylindrical surface and a ridge line 32, and the cutting edge of the first taper portion 1c is the straight portion 1 A diamond tool characterized in that the cutting allowance is larger as it is closer to a and the cutting allowance is smaller as it is closer to the second taper portion.